Passive keyless entry (PKE) and passive keyless go (PKG) systems have gained popularity in recent years. In operation, when a car user has a key apparatus that is equipped with a PKE chip and the user approaches a car and opens the door, a low frequency (LF) communication sequence is sent from the car to the key, and an ultra-high frequency (UHF) communication is sent from the key to the car via a different physical link, and the door is unlocked. Cryptology is involved in both communications to make sure the correct key and car are identified. The same interaction works with the start button using PKG. When one presses the start button, an LF communication of 125 kHz is sent to the key and the system interaction commences so that a user may start the car.
Existing communications sequences may include a code violation (“CV”) to be detected by a PKE chip to help determine synchronizations of data. A Manchester matched filter is usually not used to receive code violations. If code violations are received, two architectures are generally used to decode the CV. A system may decode the CV symbols rather than the bits. This result suffers from lower signal to noise performance. Alternatively, separate and additional matched filter(s) can be added in parallel for a wake up (“WU”) pattern and the CV to both be processed at the same time. This imposes additional overhead for an additional parallel path, which means additional current consumption.